In known prior art of heavy duty power vehicles it has been common practice to employ two or more planetary transmissions in series or parallel connection and mounted within the hub of a driving wheel as described e.g. in U.S. Pat. No. 3,150,532. However, such known wheel drive mechanisms are difficult to assemble since their various component parts can be mounted on the fixed support or spindle of a power vehicle only one after the other whereby both space and time requirements become relatively high.
A further difficulty is experienced at adjusting and mounting the wheel hub bearings. Namely, while fitting of most component parts of such drives is close and relatively coarse, bearings require fine adjustment and exact measuring of clearances which are of considerable importance as regards their lifetimes. Consequently, manufacturing of such hub wheel is very cumbersome and expensive.
The main object of the present invention is to provide an improved planetary transmission wheel drive with which mounting is considerably facilitated, and yet, fine adjustment and exact measuring of bearing clearances is reliably ensured while all advantages of known two-stage planetary wheel hub trnasmissions are still present.